1. Field
The following description relates to a network including a plurality of nodes, and more particularly to synchronization between nodes.
2. Description of the Related Art
Various methods are used to synchronize remotely placed devices with each other. In a case of using a global positioning system (GPS), synchronization between terminals is carried out to enable the terminals to have the same reference time. To this end, stationary access points (AP) which receive timing information from global navigation satellite system (GNSS) synchronize with each other, and thereafter network devices connected to each particular AP are synchronized with each other using pseudo-ranging mechanism. In addition, there is a method in which a mobile terminal equipped with a GPS receiver function receives time information and transmits the received time information to other devices connected to the mobile terminal, enabling the other devices to update their time.
In a packet switched data network, there may be used a method for clock synchronization in which a time for transmission between a master node and a slave node is determined through synchronization packets, allowing the transmission time among the nodes to be the same. In addition, there is a method for time synchronization between a clock of a master node, a clock of a bridge node, and a clock of a slave node through a synchronization message and a delay request message by using standard time transmission protocol.
The synchronization method using GPS, however, is inconvenient since a GPS needs to act as a reference clock and all nodes are thereby required to receive GPS signals. The synchronization method using synchronization packets may cause nodes to have a time delay and synchronization errors when processing packets since a physical layer (OSI layer 1) and a data-link layer (OSI layer 2) need to be taken into consideration throughout the synchronization process in order to increase time precision.